CpG island methylation status of miRNAs in esophageal squamous cell carcinoma

Previous studies on esophageal squamous cell carcinoma (ESCC) indicated that it contains much dysregulation of microRNAs (miRNAs). DNA hypermethylation in the miRNA 5′ regulatory region is a mechanism that can account for the downregulation of miRNA in tumors (Esteller, N Engl J Med 2008;358:1148–59). Among those dysregulated miRNAs, miR‐203, miR‐34b/c, miR‐424 and miR‐129‐2 are embedded in CpG islands, as is the promoter of miR‐34a. We investigated their methylation status in ESCC by bisulfite sequencing PCR (BSP) and methylation specific PCR (MSP). The methylation frequency of miR‐203 and miR‐424 is the same in carcinoma and in the corresponding non‐tumor tissues. The methylation ratio of miR‐34a, miR‐34b/c and miR‐129‐2 is 66.7% (36/54), 40.7% (22/54) and 96.3% (52/54), respectively in ESCC, which are significantly higher than that in the corresponding non‐tumor tissues(p < 0.01). Quantitative RT‐PCR analysis in clinical samples suggested that CpG island methylation is significantly correlated with their low expression in ESCC, 5‐aza‐2′‐deoxycytidine (DAC) treatment partly recovered their expression in EC9706 cell line. We conclude that CpG island methylation of miR‐34a, miR‐34b/c and miR‐129‐2 are frequent events and important mechanism for their low expression in ESCC. DNA methylation changes have been reported to occur early in carcinogenesis and are potentially good early indicators of carcinoma (Laird, Nat Rev Cancer 2003;3:253–66). The high methylation ratio of miR‐129‐2 indicated its potential as a methylation biomarker in early diagnosis of ESCC.

[1]  H. Hermeking.  p53 enters the microRNA world. , 2007, Cancer cell.

[2]  Y. Fujii,et al.  Expression profiling of micro-RNAs in human esophageal squamous cell carcinoma using RT-PCR , 2009, Medical Molecular Morphology.

[3]  A. Schetter,et al.  MicroRNA Expression in Squamous Cell Carcinoma and Adenocarcinoma of the Esophagus: Associations with Survival , 2009, Clinical Cancer Research.

[4]  Avrum Spira,et al.  miR-129 regulates cell proliferation by downregulating Cdk6 expression. , 2010, Cell cycle.

[5]  Andrew Feber,et al.  MicroRNA expression profiles of esophageal cancer. , 2008, The Journal of thoracic and cardiovascular surgery.

[6]  Michael Hallek,et al.  miRNA deregulation by epigenetic silencing disrupts suppression of the oncogene PLAG1 in chronic lymphocytic leukemia. , 2009, Blood.

[7]  M. Toyota,et al.  Epigenetic silencing of microRNA-34b/c and B-cell translocation gene 4 is associated with CpG island methylation in colorectal cancer. , 2008, Cancer research.

[8]  Elaine Fuchs,et al.  A skin microRNA promotes differentiation by repressing ‘stemness’ , 2008, Nature.

[9]  Xabier Agirre,et al.  Epigenetic regulation of microRNA expression in colorectal cancer , 2009, International journal of cancer.

[10]  S. Ropero,et al.  A microRNA DNA methylation signature for human cancer metastasis , 2008, Proceedings of the National Academy of Sciences.

[11]  G. Packham,et al.  MicroRNAs: key players in carcinogenesis and novel therapeutic targets. , 2009, European journal of surgical oncology : the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology.

[12]  Lin He,et al.  The guardian's little helper: microRNAs in the p53 tumor suppressor network. , 2007, Cancer research.

[13]  V. Tarasov,et al.  Differential Regulation of microRNAs by p53 Revealed by Massively Parallel Sequencing: miR-34a is a p53 Target That Induces Apoptosis and G1-arrest , 2007, Cell cycle.

[14]  M. Siddiqi,et al.  Aberrant promoter methylation and reduced expression of p16 gene in esophageal squamous cell carcinoma from Kashmir valley: a high-risk area , 2009, Molecular and Cellular Biochemistry.

[15]  P. Saldiva,et al.  COX-2, MMP-9, and Noguchi classification provide additional prognostic information about adenocarcinoma of the lung. A study of 117 patients from Brazil. , 2004, American journal of clinical pathology.

[16]  Xiaoling Lin,et al.  Epigenetic repression of microRNA-129-2 leads to overexpression of SOX4 in gastric cancer. , 2010, Biochemical and biophysical research communications.

[17]  M. Fabbri,et al.  Epigenetics and miRNAs in human cancer. , 2010, Advances in genetics.

[18]  M. Tatematsu,et al.  DNA methylation of microRNA genes in gastric mucosae of gastric cancer patients: Its possible involvement in the formation of epigenetic field defect , 2009, International journal of cancer.

[19]  V. Levenson,et al.  DNA methylation as a universal biomarker , 2010, Expert review of molecular diagnostics.

[20]  Carola Berking,et al.  Inactivation of miR-34a by aberrant CpG methylation in multiple types of cancer , 2008, Cell cycle.

[21]  J. Cigudosa,et al.  Genetic and epigenetic silencing of microRNA-203 enhances ABL1 and BCR-ABL1 oncogene expression. , 2008, Cancer cell.

[22]  M Suzuki,et al.  Explorer Induction of microRNAs , mir-155 , mir-222 , mir-424 and mir-503 , promotes monocytic differentiation through combinatorial regulation , 2010 .

[23]  S. Takeno,et al.  E-cadherin expression in patients with esophageal squamous cell carcinoma: promoter hypermethylation, Snail overexpression, and clinicopathologic implications. , 2004, American Journal of Clinical Pathology.

[24]  C. Abnet,et al.  Promoter Methylation in Cytology Specimens as an Early Detection Marker for Esophageal Squamous Dysplasia and Early Esophageal Squamous Cell Carcinoma , 2008, Cancer Prevention Research.

[25]  Bernat Gel,et al.  miR-34a as a prognostic marker of relapse in surgically resected non-small-cell lung cancer. , 2009, Carcinogenesis.

[26]  H. Taubert,et al.  Elevated expression of microRNAs 155, 203, 210 and 222 in pancreatic tumors is associated with poorer survival , 2010, International journal of cancer.

[27]  Jørgen Kjems,et al.  Coordinated epigenetic repression of the miR‐200 family and miR‐205 in invasive bladder cancer , 2011, International journal of cancer.

[28]  Jingqin Luo,et al.  Epigenetic repression of microRNA-129-2 leads to overexpression of SOX4 oncogene in endometrial cancer. , 2009, Cancer research.

[29]  Cicek Gercel-Taylor,et al.  MicroRNA signatures of tumor-derived exosomes as diagnostic biomarkers of ovarian cancer. , 2008, Gynecologic oncology.

[30]  D. Beer,et al.  Hypermethylation of Tachykinin-1 Is a Potential Biomarker in Human Esophageal Cancer , 2007, Clinical Cancer Research.

[31]  R. Yantiss,et al.  Clinical, Pathologic, and Molecular Features of Early-onset Colorectal Carcinoma , 2009, The American journal of surgical pathology.

[32]  R. Knight,et al.  miR-203 represses ‘stemness’ by repressing ΔNp63 , 2008, Cell Death and Differentiation.

[33]  A. Nicholson,et al.  CDKN2A, NF2, and JUN are dysregulated among other genes by miRNAs in malignant mesothelioma—A miRNA microarray analysis , 2009, Genes, chromosomes & cancer.

[34]  Shinji Tanaka,et al.  miR-124 and miR-203 are epigenetically silenced tumor-suppressive microRNAs in hepatocellular carcinoma. , 2010, Carcinogenesis.

[35]  D. Valle,et al.  DNA methylation regulates microRNA expression , 2007, Cancer biology & therapy.

[36]  Yoichi Tanaka,et al.  PGP9.5 promoter methylation is an independent prognostic factor for esophageal squamous cell carcinoma. , 2005, Cancer research.